-onium, suffix
[abstracted from ammonium.]
1. Chem. Used in forming the names of complex cations that contain a more or less electronegative central atom, usu. bonded to a number of protons (or to other species that are regarded as substituents), as arsonium, carbonium, hydrazonium, nitronium, oxonium, phosphonium, tetrachlorophosphonium, etc.
| 1971 Nomencl. Inorg. Chem. (I.U.P.A.C.) (ed. 2) 20 Names for polyatomic cations derived by addition of more protons than required to give a neutral unit to monatomic anions, are formed by adding the ending -onium to the root name of the anion element. |
2. Particle Physics. [Abstracted from positronium.] Used in forming the names of bound states of a particle and its antiparticle, as charmonium, toponium.